Contour measuring apparatus

Abstract

A contour measuring apparatus including a stylus for contacting an outer surface of an object to be measured, a support arm having mounted at the distal end thereof of the stylus, a slider movable in parallel with the longitudinal directon of the support arm and oscillatingly movable and pivotally supporting the support arm about a horizontal axis perpendicularly intersecting the longitudinal direction of the support arm, a feed screw shaft threadably coupled to the slider so as to move the slider in parallel with the longitudinal direction of the support arm and a differential transformer mounted between the support arm and the slider. The counter measuring device further includes a driven gear mounted at one end of the screw shaft, a first clutch connected by way of an idle gear meshing with the driven gear and a driving gear, a motor connected to the first clutch, a second clutch coaxially connected to the driven gear, a manual handle connected to the second clutch and a rotational angle detecting device for digitally detecting the rotation of the screw shaft. In a preferred embodiment, the rotational angle detecting device includes a case, a shaft rotatably supported by the casing connected to the feed screw shaft, a rotational angle detecting disk operationally associated with the shaft, sensing means for sensing the rotation of the disk and transferring means for transferring either the disk or sensing means in a direction for compensating for backlash by an amount equal to the backlash of the feed screw shaft when rotation of the feed screw shaft is started.

I claim: 
     
       1. A contour measuring apparatus of the type comprising a stylus for contacting the outer surface of the object to be measured, a support arm being mounted on a distal end thereof of said stylus, a slider movable in parallel with the longitudinal direction of sid support arm and oscillatingly movable and pivotally supporting said support arm about a horizontal axis perpendicularly intersecting the longitudinal direction of said support arm, a feed screw shaft threadably coupled to said slider so as to move said slider in parallel with the longitudinal direction of said support arm and a differential transformer provided between said support arm and said slider, said contour measuring device being characterized by: a driven gear provided at one end of said screw shaft;   a first clutch;   an idle gear meshing with said driven gear and coupled to said first clutch;   a motor couple to said first clutch;   a second clutch coaxially connected to said driven gear;   a manual handle connected to said second clutch; and   a rotational angle detecting device digitally detecting rotation of said screw shaft, said rotational angle detecting device comprises: a case;   a shaft rotatably supported by said case and connected to said feed screw shaft;   a rotational angle detecting disk operationally associated with said shaft;   a sensing means for sensing rotation of said disk; and   transferring means for transferring said disk in a direction of compensation for the backlash between said feed screw shaft and said slider when the rotation of said shaft is started.     
     
     
       2. A contour measuring apparatus according to claim 1 wherein said transferring means comprises: a first engageable member secured to said shaft;   a second engageable member secured to said disk and rotatably support by said shaft and located adjacent to said first engageable member through a spacing corresponding to the backlash of said feed screw shaft;   a frictional mechanism provided between said disk and fixed portion of said case for regulating of free rotation of said disk;   whereby said engageable member and said second engageable member are moved by a distance corresponding to the amount of backlash of said feed screw shaft when the rotation of said screw shaft is started thereby transmitting the rotation of the feed screw shaft to said disk through said shaft and said first and second engageable members.   
     
     
       3. A contour measuring apparatus according to claim 1 wherein said transferring means comprises: a first engageable member provided in said case;   sensing means rotatably provided in said case;   a second engageable member provided on said sensing means and located adjacent to the first engageable member through a spacing corresponding to the backlash of said feed screw shaft; and   a driving mechanism for turning said sensing means in a direction of compensation for the backlash of said feed screw shaft by a signal for starting the rotation of said feed screw shaft so as to cause the first and second engageable member to abutt on each other.   
     
     
       4. A contour measuring apparatus according to claim 3 wherein said driving mechanism comprises an electromagnetic clutch. 
     
     
       5. A contour measuring apparatus of the type comprising a stylus for contacting the outer surface of the object to be measured, a support arm being mounted on a distal end thereof of said stylus, a slider movable in parallel with the longitudinal direction of said support art and oscillatingly movable and pivotally supporting said support arm about a horizontal axis perpendicularly intersecting the longitudinal direction of said support arm, a feed screw shaft threadably coupled to said slider so as to move such slider in parallel with the longitudinal direction of said support arm and a differential transformer provided between said support arm and said slider, said contour measuring device bein characterized by: a driven gear provided at one end of said screw shaft;   a first clutch;   an idle gear meshing with said driven gear and coupled to said first clutch;   a motor couple to said first clutch;   a second clutch coaxially connected to said driven gear;   a manual handle connected to said second clutch; and   a rotational angle detecting device digitally detecting rotation of said screw shaft, said rotational angle detecting device comprises: a case;   a shaft rotatably supported by said case and connected to said feed screw shaft;   a rotational angle detecting disk operationally associated with said shaft;   a sensing means for sensing the rotation of said disk; and   transferring means for transferring said sensing means in a direction for compensating for the backlash between said feed screw shaft and said slider when the rotation of said shaft is started.     
     
     
       6. A contour measuring apparatus according to claim 5 wherein said transferring means comprises: a first engageable member secured to said shaft;   a second engageable member secured to a said disk and rotatably supported by said shaft and located adjacent to said first engageable member through a spacing corresponding to the backlash of said feed screw shaft; and   a frictional mechanism provided between said disk and a fixed portion of said case for regulating the free rotation of said disk.   
     
     
       7. A contour measuring apparatus according to claim 5 wherein said transferring means comprises: a first engageable member provided on said case;   sensing means rotatably provided on said case;   a second engageable member provided on said sensing means and located adjacent to said first engageable member through a spacing corresponding to the backlash of said feed screw shaft; and   a driving mechanism for turning said sensing means in a direction of compensation for the backlash of said feed screw shaft by a signal for starting the rotation of said feed screw shaft so as to cause said first and second engageable members to abutt on each other.   
     
     
       8. A contour measuring apparatus according to claim 7 wherein said driving mechanism comprises an electromagnetic clutch.